Add quick script to estimate ROM footprint
diff --git a/scripts/footprint.sh b/scripts/footprint.sh
new file mode 100755
index 0000000..a11844f
--- /dev/null
+++ b/scripts/footprint.sh
@@ -0,0 +1,52 @@
+#!/bin/sh
+
+set -eu
+
+CONFIG_H='include/mbedtls/config.h'
+
+if [ -r $CONFIG_H ]; then :; else
+    echo "$CONFIG_H not found" >&2
+    exit 1
+fi
+
+if grep -i cmake Makefile >/dev/null; then
+    echo "Not compatible with CMake" >&2
+    exit 1
+fi
+
+doit()
+{
+    NAME="$1"
+    FILE="$2"
+
+    echo "$NAME:"
+
+    cp $CONFIG_H ${CONFIG_H}.bak
+    cp "$FILE" include/mbedtls/config.h
+
+    {
+        scripts/config.pl unset MBEDTLS_NET_C || true
+        scripts/config.pl unset MBEDTLS_TIMING_C || true
+        scripts/config.pl unset MBEDTLS_FS_IO || true
+    } >/dev/null 2>&1
+
+    CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld \
+        CFLAGS='-Wa,--noexecstack -Os -march=armv7-m -mthumb' \
+        make clean lib >/dev/null
+
+    OUT="size-${NAME}.txt"
+    arm-none-eabi-size -t library/libmbed*.a > "$OUT"
+    head -n1 "$OUT"
+    tail -n1 "$OUT"
+
+    cp ${CONFIG_H}.bak $CONFIG_H
+}
+
+# creates the yotta config
+yotta/create-module.sh >/dev/null
+
+doit default    include/mbedtls/config.h.bak
+doit yotta      yotta/module/mbedtls/config.h
+doit thread     configs/config-thread.h
+doit ecc        configs/config-suite-b.h
+doit psk        configs/config-ccm-psk-tls1_2.h